Seatbelt systems are in widespread use in motor vehicles. Present systems have certain common elements including seatbelt webbing which extends across the upper and lower torso of the occupant, and one or more retractors for allowing protraction and retraction of the webbing so that the belt may adapt to different sizes of occupants and seat positions, and be conveniently out of the way when not being used. Seatbelt assemblies of the so-called active type further typically include a buckle to which a latch plate is releasably attached.
Seatbelt systems must be securely affixed to motor vehicle structural elements in order to provide the necessary restraint effect in vehicle impact conditions and further to meet government regulation requirements. Further, seatbelt systems need to provide “comfort and convenience” features allowing the occupant easy ingress and egress from the seat under a variety of conditions and situations, and comfort during use.
Typical seatbelt systems include a buckle that is securely mounted to a vehicle structure, such as a seat frame or the floor pan of the vehicle body. The latch plate is attached to the seatbelt webbing. The seatbelt webbing is fixed to the vehicle structure at one end, and the opposite end is usually fixed to a webbing retractor having an internal spool providing protraction and retraction of the webbing in response to various loads, while permitting buckling and unbuckling of the system. The latch plate is typically attached by passing the seatbelt webbing through an opening or slot in the latch plate, such that the latch plate can slide along the webbing and be adjusted relative to the size of the occupant, or it can be fixed to the webbing when multiple retractors are used. A common buckle configuration is in the form of a housing that includes a pushbutton release. An insertion slot is provided to receive the latch plate. A release pushbutton is provided to release the latch plate from the buckle.
In modern high-performance seatbelt restraint systems, pretensioning devices are increasingly utilized. A pretensioner tightens the seatbelt against the occupant in anticipation of a vehicle collision (a so-called pre-pretensioner), or when the onboard sensor system detects a vehicle impact. Various types of pretensioning systems are available which have the effect of reducing slack in the belt system and lost motion between the occupant and the belt system during a vehicle deceleration, which enhances restraint system performance. One type of pretensioner is referred to as a retractor pretensioner and these types normally have a pyrotechnically driven internal device acting on the retractor spool which retracts webbing into the retractor in response to a signal from a body safety controller. Examples of these devices are the applicant's roto-pretensioner products. Another pretensioner type often referred to as a buckle pretensioner, pulls the buckle rapidly toward its anchorage on the vehicle seat or vehicle floor pan. These devices are also typically pyrotechnically activated. These devices are also referred to as lap pretensioners or linear pretensioners. In addition to acting on a seatbelt buckle, similar devices can be implemented to tighten the seatbelt by moving another belt system anchorage point such as a guide loop. An example of a lap pretensioner which may be used with the present invention is described by applicants issued U.S. Pat. No. 7,188,868 which is hereby incorporated by reference.
Pretensioners attached to a seat belt buckle may be connected via a metal strap or a cable, typically of a braided wire type and often with a plastic outer covering. When cables are used, the cable is typically wrapped around a rivet attaching the cable structurally to the frame of the buckle which enables the system to oppose significant restraint loads and meet applicable structural regulation requirements. There is a concern when implementing a cable type system at its attachment to a seatbelt buckle with a buckle pretensioner. In such systems, a very rapid acceleration of the buckle occurs in the retraction direction of the pretensioner when the pretensioner is activated; and when the pretensioner reaches the end of its travel, the buckle can continue its motion due to inertia which can cause the cable to be pushed into the buckle housing. The buckle housing internal mechanisms must operate effectively in a variety of conditions. The potential for the cable protruding into the buckle internal mechanism, also referred to as cable protrusion, is a condition which is not desirable. Moreover, today's seatbelt buckles and belt restraint systems are highly refined designs and is desirable to not require reworking of the components of the belt buckle which can involve significant manufacturing and tooling costs.